Telephone-exchange system.



E. E. CLEMENT,

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED MAR. Z?. 1905.

E SHEETSMSHEET L ri, KHE

. ,lwinynd E. rl L Panted July 6, 1915 3 SHEETS*SHEET 2 E, E. CLEMENT.

TLPHONE EXCHANGE SYSTEM,

AFPLCATlON FlLED MAR. 2,1" i905.

E. E. CLEMENT.

TELEPHONE EXCHNGEYSYVSTEM.

APPLlcATioN me@ MARJI, |905.

` Patented Juy 6, 1915.

mmm

sasl' AVAILABLE corr A if; .j @111.122 www @Zwem Bea {noyvn thatjl, EDWARD E. CLEMENT,

a itienfpoiltlieslnited States, residirg at `..;in `tlre District of Columbia,

\.e.`lgy ent 'new and useful Im- ;prdvements ...Telephone-Exchange Syswhichfthefollowing is aspecifica- ,tifom-freferencerbeing had therein to the ac- -m'mperiring-.dreivea gchaugesystems, andQhas -for its object the areran-gements@ 1a-.system which shall centhe 'detailed;y description hereina iter given.

-' large cities it`-is not always practicable 'aolitoseri'eI-:all .subscribers from one central tz poin't,"lfon.eaccount principallyof the diff izit the'sebranchfexchanges, all the operators viciulty'-ggfalid 'fe'xpensefof cable' distribution.

ihand the saving in cable by a 'judicious divi- "sion ot exchanges is proportionately Very fflargaas theenumberf; of trunks required .to

covel al givenrf territory is Y necessarily less 5 thanthe number. L of individual lines.

Accordingt :the f present invention I grpupqysubscribersfaccording to their location 'i'idjc'onnecteach group to a-group or n xchange-.i -There are no operators 'f 'fbein'glcatedfat one v-selected,central point,

5f);1 chang l .which de'signatef the clearing house.

rancheichange Vis equipped .with automatic te MW' ,Each

'faiomftiiallyiconnects him with an idle trunk *iiii'rleadig'tthe clearing house,an-1i there i t 1" glljbec'ir'i'es apparentto' an operatonsincex's all terminate like ordinary es 'old-fashioned mul- Specification of- Letters Patent. l

'ble'.,the-labor om connecting subscribers ch.as' 1possible, shall divide apparatus stribute `cablefa's 'economically as may and sha-lliaccgmplish sundry other purposesfwhich .Willi s ufliciently appear .rom

following description and claims.

Onthe other call.

theV maximum load: A subscriber albo'iinectin takesA down re` whereupon -aiswitch at hisbraneh' ex- 'whiformslthe terminal of 'nis'line l' l 313icrniunirrgorfwnsirinsron, nrsrrnicr'or COLUMBIA, nssIGNomnr-Mnsnn iassrsmzrnn'rs 'ro/rnEDnn-Ioxffo. srnv'nns', forfnmfracasnnwgyonn 'A Appiication med Merch 27,1905. serial No. 252,306.

tiple switch board, on answering jacks, with which are associated line signals. The op.-

erators handle the trunks as they would subscribers l1nes-, rece1v1ng the calls and connecting without any difference; but each operator has an impulse transmitter, or' if -necessary several,by-'which sheselects the ,son Patents No. 815,176, dated' March 13,

19.06, and No.'815,321, dated March 13, 1906, with the exception that I use more wipers multiplication. A The switches Z andZ2 make use of a rotary spindle similar to that of the switches shown in thev patents cited, this being a common mechanical expedient in automatic systems. v

My invention includes many details of construct-ion, which will appear from the lVIynvention is'illustrated in panying drawings, wherein--- Figure l shows the subscribers station terminating'in a selector switch at a subthe accomexchange or station, also the sub-exchange end of the central oiiice trunk containingthe .connector switch. F ig. 2 is a similar dia'- gram showmg the central oice ends of two two way trunks, one being used to illustrate `an incoming call,theother for an outgoing The cord-circuitv is .also shown, which forms the connecting link between these trunks. F ig. 3 is a duplication of Fig. 1, and is used kto illustrate a two way trunk being used 'for an outgoing call, Fig. 1 illustrating a two way trunk being used for an incoming call.- A l f.

The apparatusand wiring in both Figs. l

fand being identica-Lfthe saine lettering'is 'observed throughout..

Referring"v now .to Fig.. 1, A ,iS-.th subscribers station. equipped with `apparatus usual in common battery systems. 'It consists'gof transmitterT,"recei\er R, ho'okH,

j ringer -Q and condenser C.. The-linef/wires 1A and 2`from this station terminate'i'n the A-wipers z.and :22 of the selector switch Z,

l'and more contacts which vonly amounts to which has associated with it the following;

.the line-relay M, retardation coil N', which su'fpply batterycurrent for talking and signaling: relai' S, actuated bythe relay M,

which controls thewibrating oi' rotary magnet sy relzty S' controlled by the wiper M of the trunk connect-or Z' for outgoing calls;

tion to this apparatus I hav e added the cut-' o relay So'for the pnfose of cutting o' spectirely,

the-vertical and rotaryr` ays S7 and SS, reand short-circuiting the condensers C2, C3, while the trunk is-being used.' I have also added the wiper 213 connected to one terminal of the relayA S9 by the wires l() and G9. There is also added the additional wiper a connected to battery for the purpose of cutting ot the operating mechanism of the line selector switch in outgoing' calls by energizing the relay S'. The springs 215 and z are controlled by the spindle 29 when it steps `up in to vertical position for the pnr`- pose of making the trunk busy for an iacoming call. e e

Referring now tothe first selector switch one terminal of the line-relay M is con'- nected to wire 1 by wire 3, the other terminal 'being grounded. The contact m* is connected -to the multiple-contact .223, of the trunk connector switch bythe wire 8. This same contact is also connected to the contact'a2 of the relayA S', and from there to th'ewinding of the relay S by the following` path: contact s3, wire 7, contacts ai', z, wire 14. relay S. It is also connected to the front contact aT of the relayS by the' wires 12 and 7 The contact m3 is connected to the multiple-terminal bv wire 18. The contact m2 is connected to the release magnet IV by the following path: wire G. contacts 27 z8,-

wire 16. and magnet IV. The retardation coil N' is connected to the line-wire 2 by the wire -t and to battery B by wire -23. One terminal ot the relay S is connected to the multiple-contact 225, in the trunk connector switch by the wire 9, the other terminal being grounded. One'terminal of the relay S is connected to' battery by the wires l0 and 23, the other terminal asv before stated being connected to the contact fm of the relay M. 'Ilie contact .S5 is connected to the rotary is connected to tlie wiper a by the wire 13, and the wiper s* is grounded.

The contact stice end ot' the trunk from the sub-stationv terminates in springs y' and j', respectively,

, of the jack J. The trunking apparatus consists ot' the signal relay M', one terminal of which is connected. to the trunk-wire'N.

'20 by the' wire 26, the other terminal being grounded through the wire 25, ,contacts fn' and a2 of the cut-ott relay if. The relay M' jointlycontrols the busy lamp n and directly controls the signal lamp m. One terminal of the cutof'f relay N is connected to the thimble j2 ot the jack'J by thel wire 32, the other terminal'being' connected to battery by the,i wire 27. Relay N jointly controls the busy lamp n and disconnectsthe signal relay M', when energized. I have thus described the central otice end of the incoming trunk, and as the central oliice end ofthe outgoing trunk is identical it will need of no description. The cord-circuit consists of the following: the answering plug P, calling plug P', supervisory relay S2, retardation coilI, controlling relay S, answering supervisory lamp S9, calling supervisory relay S3, retardationccil I", controlling relay S5. y calling supervisory lamp s1", automatic trunk disconnect relay S.V The tip p of the answering plug Pis connected to the tip y;

of the calling plug P by the following path: strand 21. contacts k, L" ofl the listen ing key K, condenser C, contacts le* and L;i of the key K' and strand 23. The sleeve -p of the answering plug P is connected to thi sleeve pof the calling plug P' by the lfol lowing pathrstrand :22,- contacts k2 and c of the listening key K, condenser C',con tacts Ic and k7 of the key K' and strand 9.4 The relay S2 is connected to the strand 21 bj the wire 36 and to ground by thel wires 3 and 34.. One term-inal of the retardatioi coilI is connected to the strand 22 by th wire 37, the other' terminal being connect connected to the strand 23 by wire 38. Tl

contact 81 is connected to battery by' tl wires 45 and 44, and one terminal ofthe r lay S3 is connected to the strand 231by wi. 38, the other terminal being vconnectedl ground through the wireiO, and contact z is connected to battery bywire- One te minal ot' therelay S5 is connected to tl third conductor p2 ofthe calling plug P l wire 46, the 'other terminal and tl conta s being connected to. ground. ig, 3 bei! identical withl Fig. 1, will need of no de- A'scriptioinf:but the operation will be explained inthe'properorder.A f:

Tlie operation of my 'system is astollows: {Rferriiigfnow :to lfig' "-1, the- Vsubscriber re i `inotingihis:telephone' closes the circuit, of -the'line-relay M-,ffwhich attracts its arma f-tiires and Vcloses the circuit of the relay S by t`h`e" -following path: ground, contacts m', m",wiie-'Sfeontacts s3, s? of the relay S', f'fwire 7,fcontaets .z5-'and 26, Wire 14, relay S #to lbattery.',"VTherelay S then being enerf-gizedattractstitsfarmatures and closes the f, 'ircuit of'ithe-'rotary-magnet s by the follow- ',15-""-ingipatlr battery '13. wires 23 and 10, con- ""tactss, S, wire 11, magnet s, contact s to f ground i The magnet s-,thereupon begins to vibrate causing the spindle ,carrying the -f-a\-ipe1"s.'e^.,. z2v;3 and z* to rotate. rThe instant y.ZOi-fthis'switclrbegins to rotate, the contacts 25, "i "s 'are :brokeng-Which opens the circuit be- ."tween the winding of the relayS and the icontact#:mint-the relay M. The relay S, l'i'oweretgds not de'e'nergized until the proper lmnltiplecontacts 219 fails to find a grounded one,v it being held up in the meantime on iff-*account ofthese ygrourided contacts coming '-'into'connection^with wiper z3, which is con- "'nected-"to'the contacts, which is now engaged with. the `contact 8S through the winding to battery When the wiper z3 finds an "1idflefcontact,that is one free from ground, v -xthe'relay S lvbecomes denergized, opens the ""rcontacts s" and' Ysfpwhich disconnects the vii -fbratingforrrotarymagnet s. lVhen the spin- "f'r dlrezftirstfbegan tozrotate, it closed the confifta'cts 127,25, which-:placed the release magnet -lVfunde'r the control of the calling sub- .3 0' Yscriber bythe-following path: batter i B.4

wires 23pand 15,117, wirek 16, contacts 57 and .g '282,'wir'eb7 contact m2 of the relay7 M. Then 'the calling subscriber hangs up his tele- .phone atthe end-ot a conversation, the cont-` tactsfm?4 .andi-971K are closed, thus operating L the releasefinagnetl. iVhen the relay M .wasilirstenergizedit placed ground on the multiple c'ontactsezf of the connector switch -f'itrnnk by 'thevfollowing path: wire 8, conet'actsm., mtofground. This makes this line busyfor an` outgoing call as in the Strowger syste-in. At-the same time a ground is placed -1-.-;-inthe multiple-contactz2tof the trunk conhectorv switch by the following path: wire `18.',3contacts mayand m to ground. This ef ground Ybeing placed on the contact e has no-:bearing on .anfincoming' call, but on an outgoing call serves to energize the cut-oli relaySoacuttingoi' tlieyertical and rotary vrelays and s hort-circuiting the condenser-s .5f in -theconnector switch duringeonrersation.

w 'lhejiinstantvthe.wiperz3 found an idle con- -.;tact, the relay S became, denergized and the 'wibratingI magnet a was disconnected and the 425'1t-ime, or until t-hewiperza in passing over the .condensers C2 and C3. The trunk .leading to The sub;

the clearing-house is now clear. scriber is now connected to an idle trank leading to the central oiiice or clearing-house by the. following path: Wire 1, wiper e,

contact a, trunk-wire 19; in Fig. 2, y' of the,

jack J, wire 2, Wiper z2, contact als, trunkwire 20, and j 'of the ljack J. This connection being completed, the signal relay M, Fig. 22, is placed in series with the retardation coil X', Fig. 1, by the following path: battery B, wires 23, 4,- 2, contacts e?, s, wires 20 and :'26, M', wire contacts n', u2 of the relay N to ground. The relay M' thereupon becomes energized and attracting its armature causes the signal lamp m to glow by closing the contacts mi and m6. The busy-lamp n is also caused to glow by closing the contacts mi and m6. This busy lamp is multipled in each position and noti'- ies the other operators that this particular trunk is busy. The operator upon perceiving the line-signal inserts the answering plug P into the jack J causing battery to How through therelay S4 and the cut-off relay N in series by the following path: ground, wire 34, relay S4, wire 33, ',02, jg, wire 3i), N, wire 27 to battery. T he relay becoming energized attracts its arniature, llisconnects the relay M by breaking vthe contacts nan'd n?, extinguishing the line signal m. The contacts n and n3 are closed, causing the busy `lamp n to continue glowing. The relay S2 being in multiple with the line relay M, F ig. 1, is energized, attracts its armature, breaking the contacts s and 812, preventing the lamp s from glowing-as The operator upon finding what number is .desired inserts the calling plug P into a trunk jack J leading to a connector switch in fa sub-exchange containing the multiple contact-of the line desired. This insertion causes battery to iiow through the relay and the relay N2, in series, by the following path: ground. S, wire 46, [12, jz, wire X2. wire 5l to battery. The relay N2 becomingenergized attracts its armature and disconnects the line-relay M2, and at the same time closes the contact leading to the busy lamp 71,4 causing it and its multiple lamp in theother positions to glow, notifying the operators v this lamp circuit was completed bythe clos- .ing of the contact-s of the relay Si 'hundred numeral ol the ard form. which will transmit impulses allecting the vertical and rotar;Y relars in the connector switch. rl`he operatori-orill only hare to manipulate her sender twice.

rThe first time to transmitthe' ten numeral of the line wanted andthe second time the unit numeral ot the line wanted, having in the. meantime learned the thousand and line wanted from the calling subscriber in answering the call.

In operating her sender the first time` inihas come' in over the-wirei, onennpu'lseis nects the' wiper. e to the' magnet'l/V2 through ter the last impulse by the tollowingp'ath terminal 'noa' resting on the desired line the.

sent in overthe trunltwire 55,' atfectingthe rel-a5v SS. whereby it attract-slits armature and energizesv the relay X causing the side switches to malte one step, thus lcutting ed 'the vertical magnet sttand in its place eut-- ting on the-rotarv magnet 835. Italso conthe side switch ,22? and contacts relay X when it is energized. sl

The operator in operating lier sender the x2, .r3 ,of the second time' transmits impulses o'rerthe Hrunlewire 5 atecting the relay Si, which now in turn operates the Vrotary inagi'iet s3". rl`his rotary magnet while operating causes the 'spindle -29 to rotate. and conie opposite the contacts leading to the desired line. Atha-s been sent in .oreitsunk wire 5l, one impulseis sent in over the trunk wire -aii'ecting the relay SS, which operates therelav X., The relav X -causes the side switches to malte one more step which disconnects the. rotary magnet .s-f through the side" switch 51.7, grounds the wiper e through the sideswitchgz" and connects the wire 5G, tothe wiper .21, .by the following path: contactsg/ and y of' relay Y. wire side switch 51S, wire 130, wiper zli. AIt also-connects the wire 5T to thewiper e bv the following `path-z contacts 'L1/3 and 'z/arire 59.' side switch 121. wire G1, wiper e, Thelast movement .of the e cuts-ontheringing relay Y and places. it under control of 'thewiertical relayfST battery, :wine SQ, Y. wire Si'. side; switch wire '76,.cont-acts .1. ot therela'y X,"wii'e contacts 824. of the relayY Sito ground-.1 The, trunkv 'iperator pushes the ringing button connectv cuits "the condensers- G2,

S3, Fig.

Arelay M, Fig. 3, of the Side ,switch placing it l under generator' current out.v over the wipers 21"' and e to the line.' of the called subscriber.

The.- spindle 59, Fig. 3. in nialting its first rei-tical 'step closes the contacts 5125.1", grounding the multiple contacts .am in the banksv of the line selector switches. malting this particular trunk bus\v for incoming calls. The .wiper 1 coming.-intocontact with' the terminals 'f' energizes the relaiv S ot' the line selector switch. causing i: to attract its armature,`disconnccting the start-v ing mechanism of that switch.v for it is evident that the relay ai being energized when the called subscriber answered. the rotarv magnet will atcncestart. and so the ioregomg means are. provided for, pre-venting this. The wiper EP3 leadingto the cuto' relay S is in connection with theterminal -s",`leading to the normally/open contact ams-ot the line-relav Mr rThe called vsubscriber upon answering closes the circuit of the line-relay M, which at once becoming.

energizing the cut-ott relay1 'Swvhich attracting its armature disconnects relays ST and SS, respectively, by breaking 'the contacts 25, 829 and 33H3. #It-also shortcir. A C3,- respectively, by .closing the contacts 82S, s39- and 325, S31.' The called subscriber is now connected straight through to the clearing house or central otticeorer line-wire J[(041, by the following path: wire 5, 521, 210, wire GOv side switch 21S, wire'S, contacts 'y and y ol the relay Y, wires 56 andji, contacts s3", .sg ot' the relay S9, wires 62,54, and p of the calling plug P, and over' No, 2 side of th line by the following path: wire 17,222,211 wire 61. side switch 219, wire 59, contacts y3 y* of the relay Y, wires 57 and 65, contact: .523,831 ot' the relay S9, wires G3 and j and 71 of the'calling plug P. The rela: 2, being in multiple with the rline called subscriber line, becameA energized when he 'removedfhi telephone, which extinguished lthe lamp s notit'ving the operator at the clearing-lions that the call is answerer. At the end of th conversation, calling` subscriber hanging u his telephonecpens the 'circuit of the line 1 and 2*. which denergizes the line-rela M, closing thecont'act's m and m?.Y The'ri leasevniagnet W is now' energized andra tracts the latch zo, releasing'the spindle .which swings around in its normaljp'ositioi A.openspthe contacts 27 es, disconnectingtl ireleaseinagnet u I Y z5 and 26, closing the. 'circuit-of the relayhi and closes vthe contac controlof' the line-relay v The vwjiper 2* learing tl forv another call.

Contact 5f" opens the circuit of the cut-oli' rela;v S ot'l the -trunk connector switch Z'. whichkagavi'n connects the relays Si and'S`.

respectilielr. -t'o `.the ytrunk -wiires 554 and 35.

The short-'circuit'fis .now-falsothec'o'ndensers'C2 and C3.

' Referring to: Fig.' fthe relay S2 also becomes".denergized 'and the circuit ofthe lamp S is closed, causing it to glowQnotitying the operator that the calling subscriber has hung uphis telephone. J The contactss15 and el .are now closed and the rela;v SG has its'circuit partl \Y completed b v the Vfollowing path: ground. contacts's, :81S 'of the. relay'S. wire l1, SG. contacts 5:15, s1, wire 43 to the 'contact' s of the rela)v S3. 'The called subscriber in hanging up his telephone open's'the'circuit of the line-rela)- VM'V i. of the line"selector-switch ZHFig. which becoming denergized opens the contacts m',

leasingr the cut-oil. relay S'q of the conu ,-"switchvZ"` 2, connecting the relays S7 andil'Ss, respectively. to the trunk wires 5i vand and Aalso remoxing the short-circuit from the condensers C2 and C3. The relay 5S, Fig. Q. also became de'e'nergized when the called subscriber hung up his telephone, and

its armature falling back closes the contacts 812s, completes the circuit of the lamp 81 causing itA to glow` also completing the circuit of the rela)` S6. The relay S, now becoming energized attracts its armature and connects batter)v to the Vertical and rotary relays ST and SS. Fig. '3. b V the following paths: battery, Awires ll, 4:5, contacts 819, s, wire 38, contacts if, strand 23, p, j, trunk wire 54; and in Fig. 3, wire 6:2,` contacts s, S29, of the rela)1 S9, wire 66, relay S7, wire 68 to ground', and from battery, wires' el, l5, contacts s, s2, wire 42, contacts k6, strand 24. p', j', trunk wire 55; and in Fig. 3, wire 63, contacts S31 and S32 of the relay S9, `wire v67, relay S8, wire 68'to 'ground Bothrelays S7 and Ss are energized simull v-taneouslvfover both sides .of the trunk `wire .by battery to ground and attracting their armatures close the contactss, s, completing thecircuit of the'. release magnet Il, which when energized restores the connector .switch Zg; to its normal position.- Therelay S, Fig. .2, remainsenergized or locked through `'the contacts SIE-s ofthe rela)r S5 -by the followingpath; battery, wires Il, 45,

contacts's, S22, S, wire-4 1, contacts s, s

-to ground. v Itiwillbe seen that battery be.- ingplacedupn the-strand 23, the relay S3 -becoming energied attracts its armature, breaks the contactsss, s14 and would extin- 'gilish -tl1e lamp. si".

.batter v by? the; followingpa'th z wire 3, contacts -m-,ft the relay; S?, contacts $22,281@

Thisrcontingency -is f provided vfor byfthefgterminal' of .tnqlamp leading to the contactcl?, being.connectedto ing withdraws the plugs from the jacks and the relays S and become dcincwiizcd. the frelarS disconnecting the 'la'nip "-'-and"=the irelaa'iSf releasing thev4 rela V S; which in turn Aextin'gl shes''the'lani'p 5"' 'a'nilreic'a" vthe irullv S.- .i' 1v .:,v

'In the foregi'iing description 'l have shown two -twoavay t'runksboth beingr ident-ical. using one` as .'an incoming f'trunk and 'the other asian outgoing trunk. so `it'follows that each't'ruiik can be used either for an incoming or an outgoing call as the case ma y be'. u In theannexed claims I use the terms line seeking and connector'asa'pnlied tothe switches ot' the'doublesets and groups. B Ythe. term line seeking I mean a Switch haring the characteristics coinmonl' attrib-A uted in the'artto a switch designated by that term.A The'principal vcha'racte'rist-icfof this type of switch is that itsoperation is initiatedfbi act ot' the subscriber-ami'. that it thereafter operates independentl of all di-1 I claim' and'desire to secure by Letters lIatentis:"`v v 1.' Ina telephone exchange s vstemfa' plurality of Branch exchanges. fa plurality ot subscribers lines terminating in each branch 'eXchange. a selector switch connected toand l[controlled by each line. a central lo'r-rclear ingfhou'se exchange, and two-way 'trunk lines Aconnectingthe same with the branch exchanges; -multiple-terminals Ifor each vltrunk in" a group 'of subscribers selector switches. a selector switch foreach trunk at a 'branch exchange land multiple-ter1ninals therein for the subscribers lines, and means at the central or 'cleairing-houseexchange to ,make connection with 'the trunk for yreceiving or sending signals therethrough, .eachsubscribefrffs selector switch being provided with `a cui-off relajv actuated when connection is made with the line throughia trunk selector switch. substantiall 7 as described.

In a telephoneexchange system, a plu'- ralityfofbranch exchanges. a pluralitjt7 of Subscribers. lines terminating ineaclrbranch exchange, 'selector fswitlcl Icol' nect'ed 5 to and ltzoldbf' `each li'al cht-ral rel-clear-- inglioi1se`- exchange, and P ftwofway :trunlc i ings; ,citetting the-sane wiui-:fthe-ftmmch exchanges? 'multiple #terminalsi rior/i each l 'selector 'art a's'b'elonging to a switch so' designated.'

switches, a selector switch for each trunk at a branch exchange and multiple-terminals therein for the subscribers lines, and means at the central or clearinghouse exchange to make connection with the trunk for receiving or sending signals theretluougln each trunk selector switch being provided with a cut-off relay actuated whenconnection is made with the trunk by a subscribers selector switch, substantialhT as described.

3. In a telephone exchange system, a plurality of' branch exchanges, a plurality of subscribers lines terminating in' each branch exchange, a selector switch connected to and controlled by each line. a central or clearing-house exchange, and two-way trunk 'lines connecting the same 'with the branch exchanges; multipletermainals for each trunk in a group ot subscriliers selector switches, a selector switch for each trunk at a branch exchange and' multiplelterminals therein for the subscribers lines, terminal spring-jacks and associatcdfhignal devices for the trunk-lines at the central oliice, operators connecting cord-circuits for interconnecting the trunk-jacks, signals associated with said cord-circuits. means controlledby the subscribers for affecting said signals, and means controlled by the operators for actuating the trunk selector switches, substantially as described.

4. A telephone exchange system comprising branch exchanges with subscribers lines radiating from each branch exchange, normally interconnected groups of automatic switching apparatus at each branch exchange, a central clearing house exchange, trunk lines therefrom to the apparatus groups at the respective branch exchanges, -said trunks being less in number than the number of subscribers lines'. manually controlled means at the clearing house exchange for interconnecting the trunks of the same or diiferent branch exchanges and through them subscribers lines, and means at each branch `exchange whereby a subscriber in calling will set the automatic switching apparatus in motion, to cause the same to select and connect his line withl an idle trunk line leading to the clearing house exchange, substantiallyas described.

j 5. A telephone exchange system comprising branch exchanges with subscribers lines radiating from each branch exchange. normally interconnected groups of automatic switching apparatus 4at each branchl exchange, a' central .clearing house exchange, 'trunk lines therefrom to the'` apparatus groups at the respectiye branch exchanges. said trunks being less in number than the number of subscribers lines.-1nanually controlled means atlthe clearinghouse exchange .forinterconnecting the trunks o f the same or different branch exchanges and through them subscribers lines, and means at cach nieuwe branch exchange whereby a subscriber ii calling will set the automatic switching ap paratus in motion, to cause the same to se lect and connect his line with an idle trunl line leading to the clearing house exchange and means whereby an operator may set ii motion other switching apparatus to selec. any desired line in the branch exchange ii which the apparatus is located, substantirdlv as described.

6. In a telephone exchange system. plu rality of branch exchanges, a pluraiity o subscribers lines terminating in each brano exchange, a selector switch for each ne, central or clearing house exchange. true lines connecting tne same with the bis.; exchanges, multiple terminals for the troni. in the subscribers selector switches, select;v switches for the trunk lines at the branc exchanges and multiple terminals therei -for the subscribers lines. and operator connective apparatus at the clearing hou.c exchange for interconnectii'ig the trunks. t gether with means adapted to be tempi rarily associated therewith to send selecte impulses. te work the trunk switches at tl branch excrranges, substantially as di scribed.

7. In a telephone exchange system, a mai clearing house exchange and branch ei changes connected thereto by trunk line with operators connective apparatus tor ti trunks at the clearing house, and a doub set ot automatic switches at each branch c change and comprising a set of line seekii and a set of connector switches. the co nector switch set controlled over the trunl to select subscribers lines. and the line sec ing set started inoperation over the su scribers lines to select the trunks. substa tially as described.

8. In a telephone exchange system, a pl rality of subscribers lines, automatic switc ing apparatus in groups containing doul unitscomprising connected line seeking ai selector switches, operators manual conn( tive apparatus. trunk lines therefrom to t automatic switching apparatus, a scudi'` device. and means whereby an operator ni control said sending device temporarily z sociatedwith a trunk line' to work the cc nector switches connected thereto. substa tially as described.

9. In a telephone exchange system. a pl rality of subscribers lines. double groups automatic switches for interconnecting t same comprising a -set. of line scelti switches for handling incoming callsv and Aconnected set of connector switches t'or ln (lling outgoing ca lls. and operators" conn tive apparatusfor interconnecting the ll seeking and connector switches th'rou which access is had to a calling and a call subscriber. substantially as described.

l0. ln a telephone exchange system. si

seeking;{switches'-v4 initiatedfrom the -sub- 1;' sc-mbersalines-anc operators"apparat-us m- `v cludrng. .a teljephon'ezset' and a .controlling defrice-2foi-r:interconnecting a. :calling and aI *cal-led.' 'subscribeie'by means of said switches.

.'11. irasetelephone:'exchange system. av'plua'flity.:oti'subseiiibersi lines, double groups of V-sinutomaticmsritchies comprising. normally' @tm-mk'connectedtiiie seeking'and connector switches for answering and for calling .selec- -exchangescomprising line seekingandcon- Y' 'nector switchesa'a:trunk line connecting'. said -;j,:s\itches'\1ftl1 oneanothera-nd 'with a .main clearing;housefantt means for-.effecting coning the connector switches fromtheclearmg house over tlrettrnnk connections.

13. In a telephoneexchange system, subscribers lines. double groups 'of automatic e switches for interconnecting the same coniprising line seeking and connector switches. trunk lines between the switches of the groups, connections from said trunk lines to 40 operators positions, and means manually controlled by the operators for connecting substations through said trunk 'connections and said groups of switches.

l. In a telephone exchange system, a plurality of subscribers lines, a plurality of trunk lines or connective circuits therefor` primary selector switches at one end thereof adapted to connect calling lines with idle trunks, selective switching apparatus at the other end thereotl adapted to be controlled so as to connect its trunk with a wanted line,

an operators outit comprising a telephone setand switch actuating means. a normally open branch connection from said trunk line to the operators outfit, and means to close said branch operable in responding to a call whereby the operator may ascertain thevline wanted and may actuate the said switching apparatus to 'connect the calling and the wanted subscribers, ,substantially as described.

15. In a telephoneexchange system. subscribers lines, a pluralityv of branch exchange trunk or link lines, a 'plurality ot' automatic branch exchange switching groups 'acl .fot saidl doublel'groups comand means wiherby .theoperation ot'- the flinef tion rrespectixielan operator-rs1 cir-cuits norcach lgroup comprising line seeking switch- -ing m'ean's tlie' operation of which is initiated Vt'iomt-he subscribers lines and which is a1- ranged to automatically connect aicalling line to one 'ots'ai'd' links. andV normally' connected c switch-ing means tor selecting a -wantetlflineQa'commonexchange. and connections rom'said branch links'to'said 'coinmon' 'exchange with vmeans under the control `of operators atthe 'commonexchange toactuate. theV said separate 'and additional switching means for selecting a wanted line at the branch exchanges, substantially-as -described.- I 1G. In a telephone exchangesystem. a plu- -rality of automatic branchexchanges. each containing automatic -line seeking switches for connecting calling lines to trunks and y connected separatelyoperating calling or `se-A lective switches. a plurality of subscribers lines terminatingr in saidxautomatic branch exchanges. n' and a mainclearing house ex change with means connecting it with each branch exchange and both the primary and selective switches whereby'operators ther-eatmay receiveall calls from and selectively make all connections at the branch Iexchanges. substantially as described` 1T. In a telephone exchange system'. a plu- -rality of subscribers lilies. a line seeking; switch the operation of which is initiated by the act of a calling subscriber. a `trunkvor connective circuit, thereforl terminating at .one end in contacts of the -said prinn'lry switch. and at'the other end in a selector Switch adapted when actuated by definite impulses to connect the trunk with a wanted subscribers line. an operator`s` equipment comprising a telephone set and a controlling device for said selector switches. a plug terminal for said operators equipment, and aJ cooperating jack connected with the trunk, the said selector switch being operable from the operators equipment only, substantially as described.

1S. In a telephone exchange system. a plurality of subscribers lines. a trunk or connective circuit therefor. automatic line seek-- ing and connector switches for connecting' said trunk with calling and wanted lines, respectively. an operator`s` circuit completely equipped with a telephone set and a switch controlling device separate from the trunk, and s\\'itclii11g'n1eans to bring said outfit into connection with the trunk. in responseto a call.

19. In a telephone exchange system.' a

main clearing house exchange and branch exchanges connected thereto by trunk lines. with operators` telephones and directive apparatus adapted to be. connected to theV trunks at the clearing house, and a double set of automatic switches at each branch exchange comprising a set of line seeking and a normally trunk connected set of connector l by the condition of any line automatically stopping the movement of said selector switches, the'connector switch set controlled over the trunks only to select subscribers lines, and `the line seeking set controlled over the subscribers lines only to select the sanietrunks, substantially as described.

520. In atelephone exchange' system, 'a main clearing house exchange and branch exchanges connected thereto by trunk, lines, with operators telephones and ldirective apparatusv adaptedto be connected'to thetrunks at the clearing-house, a double set of automatic switches at each branch exchange, said double set comprising a set of line seekin.g':and a set of connector switches, sub- ;ribers lines connected' inv common to switches in both'sets, and:trunklines connecting, in common, switches ofpeach set4 to the main clearing house, one of said sets, being controlled over the trunks toV select' switch." when' an idle line is reached, said means including a self-'locking 'controlling relay having its locking circuit completec' throughthe'transmission line test terminals and dependent uponthe condition thereof.

:22. In combination, ai plurality of electrical transmission lines having different busy and idle conditions, a selector switchadapt ed to connect said lines to another circuit means for actuating said selector switch t( more from agivennormal position succes sively over the transmission line terminals and a-testing relay governed bythe condi tion of'any line and acting to stop the move` mentof said selector switch when an idli line is reached, said relay after initial ener gization'locking itself through line test ter min'als. Y v

23; In vautomatic switchingapparatus, se lector switches containing multiple test ter minals, means for main'taining test potentia on terminals that are busy, and a test rela] -for each switch adapted upon initial ener gization to connect itself to the test wipe:

of the switch lthrough a circuit controlle( by itself exclusively.

24. An automatic selector switch contain ing multiple test contacts, a test wiper, and: test relay connected in operation to the tes Wiper through self-locking means'.

' In testimony whereof I have affixed mj signature in presence of two Witnesses. EDWARD E. CLEMENT. Witnesses:

HUGH M'. STERLING, 'Gr.0. M. COPENHAVR. 

